KAX53_MESMA
ID KAX53_MESMA Reviewed; 61 AA.
AC Q9TVX3;
DT 19-DEC-2001, integrated into UniProtKB/Swiss-Prot.
DT 01-MAY-2000, sequence version 1.
DT 25-MAY-2022, entry version 78.
DE RecName: Full=Potassium channel toxin alpha-KTx 5.3;
DE AltName: Full=Neurotoxin BmP05 {ECO:0000303|PubMed:10386622};
DE AltName: Full=Potassium ion channel blocker P05 {ECO:0000303|PubMed:10386622};
DE Flags: Precursor;
OS Mesobuthus martensii (Manchurian scorpion) (Buthus martensii).
OC Eukaryota; Metazoa; Ecdysozoa; Arthropoda; Chelicerata; Arachnida;
OC Scorpiones; Buthida; Buthoidea; Buthidae; Mesobuthus.
OX NCBI_TaxID=34649;
RN [1]
RP NUCLEOTIDE SEQUENCE [GENOMIC DNA / MRNA].
RX PubMed=10386622; DOI=10.1016/s0014-5793(99)00651-1;
RA Wu J.-J., Dai L., Lan Z.-D., Chi C.-W.;
RT "Genomic organization of three neurotoxins active on small conductance
RT Ca2+-activated potassium channels from the scorpion Buthus martensi
RT Karsch.";
RL FEBS Lett. 452:360-364(1999).
RN [2]
RP PROTEIN SEQUENCE OF 29-59, FUNCTION, SYNTHESIS, AMIDATION AT HIS-59, MASS
RP SPECTROMETRY, TOXIC DOSE, AND SUBCELLULAR LOCATION.
RX PubMed=9151979; DOI=10.1111/j.1432-1033.1997.00457.x;
RA Romi-Lebrun R., Martin-Eauclaire M.-F., Escoubas P., Wu F.Q., Lebrun B.,
RA Hisada M., Nakajima T.;
RT "Characterization of four toxins from Buthus martensi scorpion venom, which
RT act on apamin-sensitive Ca2+-activated K+ channels.";
RL Eur. J. Biochem. 245:457-464(1997).
RN [3]
RP MUTAGENESIS OF LYS-34; GLN-37; ARG-41; 50-ILE--ASP-52 AND HIS-59, AND TOXIC
RP DOSE.
RX PubMed=11851432; DOI=10.1021/bi011367z;
RA Wu J.-J., He L.-L., Zhou Z., Chi C.-W.;
RT "Gene expression, mutation, and structure-function relationship of scorpion
RT toxin BmP05 active on SK(Ca) channels.";
RL Biochemistry 41:2844-2849(2002).
RN [4]
RP FUNCTION, AND SYNTHESIS OF 29-59.
RX PubMed=29483648; DOI=10.1038/s41594-018-0033-9;
RA Correnti C.E., Gewe M.M., Mehlin C., Bandaranayake A.D., Johnsen W.A.,
RA Rupert P.B., Brusniak M.Y., Clarke M., Burke S.E., De Van Der Schueren W.,
RA Pilat K., Turnbaugh S.M., May D., Watson A., Chan M.K., Bahl C.D.,
RA Olson J.M., Strong R.K.;
RT "Screening, large-scale production and structure-based classification of
RT cystine-dense peptides.";
RL Nat. Struct. Mol. Biol. 25:270-278(2018).
CC -!- FUNCTION: Blocks small conductance calcium-activated potassium channels
CC (KCNN, SK) (PubMed:9151979). Has also been shown to weakly inhibit
CC Kv11.1/KCNH2/ERG1, Kv1.2/KCNA2, Kv1.3/KCNA3 and Kv2.1/KCNB1 voltage-
CC gated potassium channels (PubMed:29483648).
CC {ECO:0000269|PubMed:29483648, ECO:0000269|PubMed:9151979}.
CC -!- SUBCELLULAR LOCATION: Secreted {ECO:0000269|PubMed:9151979}.
CC -!- TISSUE SPECIFICITY: Expressed by the venom gland.
CC {ECO:0000305|PubMed:9151979}.
CC -!- DOMAIN: Has the structural arrangement of an alpha-helix connected to
CC antiparallel beta-sheets by disulfide bonds (CS-alpha/beta).
CC {ECO:0000305}.
CC -!- MASS SPECTROMETRY: Mass=3371.39; Method=MALDI;
CC Evidence={ECO:0000269|PubMed:9151979};
CC -!- TOXIC DOSE: LD(50) is 1.85 ug/kg by intracerebroventricular injection
CC into mice. {ECO:0000269|PubMed:11851432, ECO:0000269|PubMed:9151979}.
CC -!- MISCELLANEOUS: Toxicity experiments on mutants are done without C-
CC terminal amidation. {ECO:0000269|PubMed:11851432}.
CC -!- SIMILARITY: Belongs to the short scorpion toxin superfamily. Potassium
CC channel inhibitor family. Alpha-KTx 05 subfamily. {ECO:0000305}.
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DR EMBL; AF079064; AAD47378.1; -; mRNA.
DR EMBL; AF095780; AAF03044.1; -; Genomic_DNA.
DR AlphaFoldDB; Q9TVX3; -.
DR SMR; Q9TVX3; -.
DR GO; GO:0005576; C:extracellular region; IEA:UniProtKB-SubCell.
DR GO; GO:0008200; F:ion channel inhibitor activity; IEA:InterPro.
DR GO; GO:0015459; F:potassium channel regulator activity; IEA:UniProtKB-KW.
DR GO; GO:0090729; F:toxin activity; IEA:UniProtKB-KW.
DR InterPro; IPR036574; Scorpion_toxin-like_sf.
DR InterPro; IPR001947; Scorpion_toxinS_K_inh.
DR Pfam; PF00451; Toxin_2; 1.
DR SUPFAM; SSF57095; SSF57095; 1.
DR PROSITE; PS01138; SCORP_SHORT_TOXIN; 1.
PE 1: Evidence at protein level;
KW Amidation; Calcium-activated potassium channel impairing toxin;
KW Direct protein sequencing; Disulfide bond; Ion channel impairing toxin;
KW Neurotoxin; Potassium channel impairing toxin; Secreted; Signal; Toxin.
FT SIGNAL 1..28
FT /evidence="ECO:0000269|PubMed:9151979"
FT CHAIN 29..59
FT /note="Potassium channel toxin alpha-KTx 5.3"
FT /evidence="ECO:0000269|PubMed:9151979"
FT /id="PRO_0000035324"
FT REGION 34..37
FT /note="[R/K]XCQ motif"
FT /evidence="ECO:0000305"
FT MOD_RES 59
FT /note="Histidine amide"
FT /evidence="ECO:0000269|PubMed:9151979"
FT DISULFID 31..49
FT /evidence="ECO:0000250|UniProtKB:P16341"
FT DISULFID 36..54
FT /evidence="ECO:0000250|UniProtKB:P16341"
FT DISULFID 40..56
FT /evidence="ECO:0000250|UniProtKB:P16341"
FT MUTAGEN 34
FT /note="K->A: 86.4% loss of toxicity. 100% loss of toxicity;
FT when associated with A-41."
FT /evidence="ECO:0000269|PubMed:11851432"
FT MUTAGEN 37
FT /note="Q->P: 97.5% loss of toxicity."
FT /evidence="ECO:0000269|PubMed:11851432"
FT MUTAGEN 41
FT /note="R->A: 83.0% loss of toxicity. 100% loss of toxicity;
FT when associated with A-34."
FT /evidence="ECO:0000269|PubMed:11851432"
FT MUTAGEN 50..52
FT /note="IGD->MNG: 68.4% loss of toxicity."
FT /evidence="ECO:0000269|PubMed:11851432"
FT MUTAGEN 59
FT /note="H->A: 55.4% loss of toxicity."
FT /evidence="ECO:0000269|PubMed:11851432"
SQ SEQUENCE 61 AA; 6808 MW; 628B80BF2214E903 CRC64;
MHNYYKIVLI MVAFFAVIIT FSNIQVEGAV CNLKRCQLSC RSLGLLGKCI GDKCECVKHG
K
